Aluminum Feeders

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B-Mike

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Ok so I Have been discussing the topic of feeder wire size with some of my Co-workers And we can not all agree on the answer.What is the correct size
Aluminum feeder for a 208v 200A 3-p 4-wire Panel no more than 160'
in length in a commercial Building.
 
Assuming your load does not exceed 180 Amperes, you would be permitted to use 4/0 AWG AL conductors (not considering voltage drop).

Table 310.16 and 240.4(B)
 
So if my load is calculated at 145A, and my distance is 160 Ft, is 4/0 OK ?
At what length does voltage drop come in Play?
Also the terminations in a panel are rated for 75 Degrees,
do I have to run a wire rated for 75 degrees ? or is wire rated for 90 degrees OK??????????
 
B-Mike said:
So if my load is calculated at 145A, and my distance is 160 Ft, is 4/0 OK ?
At what length does voltage drop come in Play?
Also the terminations in a panel are rated for 75 Degrees,
do I have to run a wire rated for 75 degrees ? or is wire rated for 90 degrees OK??????????
Click to expand...

So the feeders are protected at 200A?
I would think that 110.14(C)(1)(b) would come into play.
Are there any terminals that are rated for 90 degrees?
Is'nt the 90 degree column just for derating?
My answer is 250KCMIL.
 
Gogreen100 said:
My answer is 250KCMIL.
Click to expand...


That would work also, although Bryan gave the correct answer for the minimum size feeder which is #4/0 Al, (75 degrees C, @ 180 amps). 240.4(B) allows you to go up to the next standard OCPD which is 200 amps.


Voltage drop for 145 amps and 160' would be about 1.8% which is fine. You can check that here:

http://www.electrician2.com/calculators/vd_calculatoradv.htm
 
infinity said:
That would work also, although Bryan gave the correct answer for the minimum size feeder which is #4/0 Al, (75 degrees C, @ 180 amps). 240.4(B) allows you to go up to the next standard OCPD which is 200 amps.


Voltage drop for 145 amps and 160' would be about 1.8% which is fine. You can check that here:

http://www.electrician2.com/calculators/vd_calculatoradv.htm
Click to expand...
Its fun to calculate, but you will usually find that you dont need to compensate for voltage drop until you get into the 300' range.
 
Aluminum Feeders

The only thing is that the breaker that is feeding the wire is 200A.
is 4/0 aluminum OK ?????? ,
ore do i have to use 250 Mcm aluminum ???????
 
B-Mike said:
The only thing is that the breaker that is feeding the wire is 200A.
is 4/0 aluminum OK ?????? ,
ore do i have to use 250 Mcm aluminum ???????
Click to expand...

4/0 AL is ok to use!!!!!!
 
B-Mike said:
Ok so I Have been discussing the topic of feeder wire size with some of my Co-workers And we can not all agree on the answer.What is the correct size
Aluminum feeder for a 208v 200A 3-p 4-wire Panel no more than 160'
in length in a commercial Building.
Click to expand...


Feeding what? What's on your neutral?
 
Aluminum Feeders

A 200A panel being feed by a 200A breaker total distance is 160'.
The total load on the panel has been calculated
At 145A by the electrical engineer. He calls for 3/0 Copper.
So i wont to use 4/0 AL my Project mangier Thinks we need to use
250mcm AL.I have always used 4/0 AL But i may have always ben wrong
So I am just tying to find Witch way is correct.
 
B-Mike said:
A 200A panel being feed by a 200A breaker total distance is 160'.
The total load on the panel has been calculated
At 145A by the electrical engineer. He calls for 3/0 Copper.
So i wont to use 4/0 AL my Project mangier Thinks we need to use
250mcm AL.I have always used 4/0 AL But i may have always ben wrong
So I am just tying to find Witch way is correct.
Click to expand...

Code wise it is easy.

240.4(B) allows the use of the next size standard overcurrent protective device.

240.4 Protection of Conductors.

Conductors, other than flexible cords, flexible cables, and fixture wires, shall be protected against overcurrent in accordance with their ampacities specified in 310.15, unless otherwise permitted or required in 240.4(A) through (G).

(B) Devices Rated 800 Amperes or Less. The next higher standard overcurrent device rating (above the ampacity of the conductors being protected) shall be permitted to be used, provided all of the following conditions are met:

(1)The conductors being protected are not part of a multioutlet branch circuit supplying receptacles for cord-and-plug-connected portable loads.

(2)The ampacity of the conductors does not correspond with the standard ampere rating of a fuse or a circuit breaker without overload trip adjustments above its rating (but that shall be permitted to have other trip or rating adjustments).

(3)The next higher standard rating selected does not exceed 800 amperes.
Click to expand...

4/0 AL is rated 180 amps and the next size standard overcurrent protective device is 200 amps per 240.6

As long as the calculated load is 145A you are good to go with 4/0 AL

However unless your offering a credit back to the customer using AL in place of copper called for is cheating.
 
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